The present invention relates to a non-contact power supply systems that supply electric power to movable bodies on rails thereby enabling the movable bodies to run on the rails.
Monorail type transfer systems are used in factories and warehouses. Such systems include a movable body, or a carriage, that conveys loads along a rail laid on a ceiling. The carriage also loads and unloads the loads at stations provided along the rail. FIGS. 9 and 10 show a system for supplying electricity to such a carriage. The system includes a power cable 102 that is located along a rail 101, on which a carriage moves. As shown in FIG. 10, the power cable 102 has a circular cross-section. The rail 101 is formed, for example, as an endless loop. This construction allows the carriage to circulate along the rail 101. The power cable 102 is a single wire that is folded at a folded part 102a to form an upper portion and a lower portion extending parallel on the rail 101. Both ends of the power cable 102 are attached to a power supply unit 108.
Brackets 104 are located on the rail 101 at predetermined intervals. Each bracket 104 has upper and lower hangers 105 projecting horizontally. The power cable 102 is supported on the distal ends of the hangers 105. A pickup unit 103 mounted on the carriage faces the cable 102 without contacting the cable 102. The pickup unit 103 generates induced electromotive force based on electrical current through the power cable 102 and supplies electricity based on the generated induced electromotive force to the carriage. The carriage moves using the electricity.
In order to allow the carriage to circulate on the loop rail 101, the folded part 102a of the power cable 102 must not contact the pickup unit 103. Thus, the folded part 102a is secured to the rail 101 by, for example, a fixing member 106. The end portions of the power cable 102 are routed away from the loop rail 101 and are connected to the power supply unit 108. These end portions also must not contact the pickup unit 103.
However, when the carriage passes by a gap between the folded part 102a and the end portions of the power cables 102, the pickup unit 13 generates lower electromotive force. This may hinder the movement of the carriage.
It is preferable to use a pickup unit 107 illustrated by a long and short dashed line in FIG. 10 to increase the generated electromotive force. The pickup unit 107 has an E-shaped cross section and is preferably located as close as possible to the power cable 102 in a surrounding manner for increasing the electromotive force. However, simply securing the folded part 102a of the power cable 102 to the rail 101 does not prevent the part 102a of the cable 102 from interfering with the pickup unit 107. Likewise, it is difficult to route the end portions of the cable 102 from the rail 101 and connect them to the power supply unit 108 without causing the end portions of the cable 102 to interfere with the E-shaped pickup unit 107.